1. Field of the Invention
This invention relates to optical networking technology, and more particularly, to an optical network transmission channel failover switching device which is designed for use with an optical network, such as a local area network used for linking Internet to the clients or a telephone network, for the purpose of providing the optical network with a transmission channel failover switching function.
2. Description of Related Art
Optical networking is a communication technology that utilizes optical fibers and laser beams for data transmission between computers, telephones and other electronic devices. Optical networks can be used to transmit signals either in analog or digital forms. Since laser beams are much higher in frequency than electrical and radio signals, optical networking is far more reliable and has far greater transmission capacity than traditional cable and radio communications.
PON (Passive Optical Network) systems are a widely employed technology for data communication between the Internet and local area networks that are used for connection to private users and small business entities. In practice, a PON system typically utilizes just one single strand of optical fiber for two-way transmission of optical signals to and from the client sites. One drawback to the traditional single-fiber two-way PON systems, however, is that when the single fiber is damaged or fractured, the data communication to the client sites is entirely disconnected. One solution to this problem is to provide two channels (i.e., two strands of fibers) in the optical transmission path: a primary channel and a secondary channel, where the primary channel is initially set to be responsible for optical transmission while the secondary channel is set to standby mode, such that in the event of a failure to the primary channel (such as when fractured), the failed primary channel can be failover switched to the backup channel.
To achieve the above-mentioned failover purpose, it is needed to develop an optical transmission channel failover switching device capable of switching the primary channel over to the backup channel in the event of a failure to the primary channel. Presently, one solution is to utilize two one-to-two (1×2) optical switches in an optical auto switch (OAS) to provide the desired failover switching function. One drawback to this solution, however, is that it lacks the capability of monitoring the backup channel to check whether the backup channel is in good usable condition when the primary channel fails. As a consequence, if the backup channel is also in unusable condition when the primary channel fails, it will cause the entire optical network system to shut down, resulting in degraded serviceability and security to network services.